It's an address book that is accessed by using option 3 in the network menu. To use it, put in other player's IP addresses in the address.txt file and save it. Then, in the network menu, option 3 will list the IPs you have put in the address.txt file for you to select (and attempt connect to).

This feature is only useful if you connect to the same players very frequently, and their IPs do not change.

EG. if you connect to the same people a lot, and their IP addresses do not change, then add their IPs to the txt file so you can connect quickly and easily.

So what should I use for the older versions?

Upgrade to full, the old demo versions are deprecated.

Can I watch or spectate other matches?

Yup, the default built-in netplay supports spectating, just connect to an IP after a game as already begun between other players and it will ask if you want to proceed.

You can also save and watch replays, so if you find some replays posted online you can watch those, too.

This is confusing, how the hell does this work!?

When you enter the netplay menu the first option allows you to host a game. The number that pops up when you select it is the port that you will use for hosting (The default is 10800).

After you press confirm, the game will begin waiting for your opponent to join using that port on your IP address, and at this point you give your IP and port to the person you want to play (you'll have to give some one your IP by yourself, the game won't do it for you). Then they can use one of the connect options (easiest/fastest being option #5) to connect to you and you can begin playing.

This will not work if you do not have port 10800 available. Sometimes ports get blocked off either by a firewall or by a router if you have either of them. So, if the port is blocked then you'll need to make a choice on what to do, which is either:

Configure or disable your firewall and/or router to allow that port to be used. See PortForward for more information on how to configure your router.

Or use a port that you can already use for other games (such as port 6112 for WoW or port 7500 for MB:AC/IaMP).

Or Join some one else's game instead of hosting a game.

I heard about Caster, I want SWRCaster

There is no Caster for SWR, there is no need for it, and there probably never will be.